There is no setting for like display being turned on when any notification comes from messaging apps, or when we have selected tap to on always on display and any notification from selected apps like messaging apps the always on display should on, although you can keep always on display on always but that ends up draining battery to much. So i guess through an update you should add this its such a basic feature.
We have noted down the feedback regarding this and providing a continues great experience to our customer is our first priority. We would take this feedback for further improvements in our upcoming software launches.
